1. Technical Field
The present invention relates methods for conversion treating surface of magnesium alloy workpieces.
2. Discussion of Related Art
Magnesium is a metal that is the lightest in weight among metal materials. Magnesium alloys are composed of the magnesium and some other metals, such as aluminum and zinc. In recent years, there has been an increase in demand for magnesium alloys used as structural materials for electronic products and vehicles.
The magnesium alloy may easily react with other chemical substances such as acids, thus, a protective layer is normally needed to be formed on the surfaces of magnesium alloy workpieces. A phosphating film is generally formed on an outer surface of a magnesium alloy workpiece to protect the magnesium alloy workpiece.
The phosphating film is formed by a method for conversion treating surface of the magnesium alloy workpiece. Typically, the method includes a chemical converting step. However, the thickness of the phosphating film formed during the chemical converting step is not easily regulated, and frequently, a corrosion resistance or a surface resistance film is not being satisfactorily formed on the magnesium alloy workpiece to meet the requirements.
Therefore, a phosphating solution and method for conversion treating surface of a magnesium alloy workpiece are desired in order to overcome the above-described shortcomings.